LAN Mirroring technologies are an important HA technology now, and will remain a key ingredient in many inexpensive HA systems. They allow two machines to mirror a filesystem between themselves with only two NICs and a crossover cable - yielding a system with no SPOF[1]s for a very low price.
DRBD[2]: system by Philipp Reisner[3] and LarsEllenberg[4] for mirroring filesystems across the LAN. It is RAID and LAN aware with a quick sync option for bringing the mirror up to date quickly. Recent versions even have a very fast full-sync option. This is the general replication technology which is most commonly used by members of the Linux-HA community, because it provides a complete solution, is sensitive to data integrity issues, and integrates easily with Linux-HA.
Enhanced Network Block Device[5] project by P.T. Breuer. ENBD is a project to make the NBD work right. It doesn't combine the NBD and RAID together like DRBD does.
Linux Journal[6] article by P.T. Breuer, A. Marin Lopez and Artuo Garcia Ares on The Network Block Device[7] A network block device (NBD) driver makes a remote resource look like a local device in Linux, allowing a cheap and safe real-time mirror to be constructed.
NBD server software[8] - the complement to the in-kernel NBD driver.
-- AlanRobertson[9]
| [1] | http://www.linux-ha.org/SPOF |
| [2] | http://www.linux-ha.org/DRBD |
| [3] | http://www.linbit.com/philippreisner.html?&L=1 |
| [4] | http://www.linux-ha.org/LarsEllenberg |
| [5] | http://www.it.uc3m.es/~ptb/nbd |
| [6] | http://www.linuxjournal.com/ |
| [7] | http://www2.linuxjournal.com/lj-issues/issue73/3778.html |
| [8] | http://nbd.sourceforge.net |
| [9] | http://www.linux-ha.org/AlanRobertson |
This information provided courtesy of the Linux-HA project at http://linux-ha.org/